Use 2nd ethernet port to improve network performance

[Lastmboy]

I'm trying to diagnose LAN performance issues. I have a 2009 Mac Pro acting as a file server and a 2013 Mac Pro as my desktop. There are gigabit switches between them with cat6 cabling. One of the switches feeds my TV and media box. I use the 2009 Mac Pro for all media downloading. My internet connection is 300 Mpbs. The problem is, whenever it is downloading anything, my LAN slows to a crawl. I am unable to watch any video from the server until the download completes. What I'm wondering is if the single ethernet connection to the server is my bottleneck. I saw someone mention that it will revert to 100 Mbps for the internet connection, so that I am not getting gigabit speeds everywhere else.

Forgive my ignorance, but is there a way to use the second ethernet port on the Mac Pro to improve network performance? i.e. could I use the one port for internet downloads and the other port for LAN access? Would I still be able to get internet access to the other devices on the network, along with gigabit speeds? I'm not sure how to configure it to test out this theory. Also, would upgrading my cabling to cat8 provide any benefit whatsoever?

Any suggestions appreciated.

 

[hobowankenobi]

There are a few things to be done. Cabling: You should not need anything above CAT6. Doubt this is a cabling issue...unless there is a problem, bad termination, or a very long run.

First, verify that everything is indeed Gig speeds. That can be done through testing, and even the network control panel on Macs (and some other devices) will verify the NIC connection speed.

With two NICs, the simplest thing to do is have 2 different IP addresses and use them for specific work. I have not done it with a Mac Pro, but on most boxes, one can simply connect to the preferred IP. Example:

NIC 1: 192.168.1.10
NIC 2: 192.168.1.11

So...use .10 to connect to the router. All internet, including downloads, would use this connection. And then connect to .11 for devices streaming content from the server. So all devices would connect to .11.

The only thing one has to configure is how DHCP is handled by your router. If, for example, your router hands out all IPs, you could start (or end) the DHCP range and leave room for static IPs. Then you can assign static IP addressed to both server NICS (per example above), so know which NIC is being used by which device.

I have done this with several different file servers with good success; some clients connect to one NIC, some connect to the second. You get to control the two lists, and spread out load between the two NICs.

So:

1. Adjust DHCP as needed on router
2. Assign static (or DHCP with manual address) IP addresses to both server NICs
3. Verify 1st NIC is right, internet access as expected, etc.
4. Verify 2nd NIC is connected in Network Pref pane
5. Connect device(s) to second NIC via IP address
6. Test throughput...both with and without downloads happening

There are more sophisticated methods of NIC bonding and specifically "link Aggregation" on Macs, but last I checked it required specific managed switches that support the protocol. Most basic/unmanaged switches don't.

 

[disconap]

Follow the above, you can set one NIC for server traffic and the other for internet.

You can also bridge ethernet NICs, but I have doubts that it actually improves performance. I am attempting something similar at the moment (started a separate thread for it as it is a slightly different case, using USB-C and ethernet paired). I'll link my thread below, but here is the basic tutorial on how to do it:

Instructions

Thread

EDIT: apparently I asked this back in November too, though before trying it. Here is the response I got:

No.
Teaming NICs doesn’t make a bigger pipe. It makes a « larger » pipe to the server. This one will be able to handle more requests, not making each one faster.